Folding trolleys are widely used in many places for transporting groceries, pets, gardening articles and the like. The existing folding cart generally has one handle and four wheels as well as a folding cart body and a cloth pocket for containing articles. The trolley may be a multi-functional trolley, can serve as a station wagon, and can also transport articles to seaside or any place. As the folding cart, one of the most important considerations is that the folding cart can be folded and stored when not used, and no large space is occupied. Therefore, in current production of domestic factories, to realize folding and storage, one structure is as follows: two narrow rotating wheels (front wheels) are adopted; a trundle fixing frame of the two rotating wheels is welded on a trolley body; and a trundle fixing frame of two fixing wheels (rear wheels) is also directly welded and fixed to the trolley body. Because treads of the wheels are narrow, folding can be realized. Moreover, after folding, the four wheels are on one straight line. But this structure has a disadvantage because the wheels are narrow, and so the stability is poor and the trolley is easy to roll over. Moreover, the trolley is not suitable for use in sandy beaches and is easy to fall into sand. Another structure is as follows: to enable the trolley to be suitable for use in the sandy beaches, wide rotating wheels are adopted. After the wheels are widened, to realize full folding, a method for sliding the trundle fixing frame of two fixing wheels is adopted for achieving a folding effect. However, this method may affect the normal use of the trolley. Because the trundle fixing frame needs to successfully slide, a certain gap must be kept. Moreover, the fixing wheels are oblique. In this way, two fixing wheels are not firm during operation, thereby affecting the loading capacity. Moreover, in a slide process, an angle needs to be regulated continuously, thereby wasting time, causing instability in use and easily damaging the trundle fixing frame. The trundle frame may be abraded due to long-term repeated slide, thereby damaging the trolley, affecting the normal use, injuring the user and affecting product reputation. Therefore, the problem to be addressed by this disclosure involves more efficiently folding the folding cart that adopts wide wheels.